The Effect of Vitamin B-12 Supplementation During Pregnancy on Early Motor Performance: Secondary Analyses From a Double-Blinded Randomized Controlled Trial.

BACKGROUND

In a recent double-blind randomized controlled trial (RCT) in Nepal, we found a negative effect of maternal vitamin B-12 supplementation during pregnancy on motor performance in their young infants.

OBJECTIVES

The objective of this study is to examine whether the negative effect of the vitamin B-12 supplementation on motor performance in these infants aged 8 to 12 wk differed by baseline maternal characteristics.

METHODS

These are secondary analyses of an RCT where 800 pregnant women were randomly assigned to receive vitamin B-12 or placebo from early pregnancy to 6 mo postpartum. The outcome was motor development measured by the test of infant motor performance (TIMP) in 712 infants at age 8 to 12 wk. We examined whether plasma markers of baseline maternal vitamin B-12 status [cobalamin, total homocysteine (tHcy), methylmalonic acid (MMA), and cB12], folate and hemoglobin concentration, and socioeconomic status (SES) modified the effect of vitamin B-12 on the TIMP scores. The subgrouping variables were categorized according to predefined cutoffs and included as interaction terms in generalized linear models, with treatment group as the exposure and TIMP scores (continuous and categorical) as the outcomes.

RESULTS

Overall, the negative effect of the vitamin B-12 supplementation was observed in most subgroups. Except for plasma folate concentration (P-interaction = 0.015), the maternal baseline characteristics did not significantly modify the effect of vitamin B-12 supplementation on the TIMP scores. There was a tendency for a stronger negative effect of vitamin B-12 among infants of women with adequate baseline vitamin B-12 status (i.e. concentrations of cobalamin >220, tHcy <10, MMA <0.26, and cB12 values >-0.5) and with folate concentration in the lower tertile.

CONCLUSIONS

The negative effect of vitamin B-12 supplementation on infant motor performance cannot be explained by any subgroup specific effects. However, the effect appears to be more pronounced in mothers with adequate B-12 status. This trial was registered at clinicaltrials.gov as NCT03071666 (https://www.

CLINICALTRIALS: gov/study/NCT03071666).